Year Number 2004-01-01 0.1825 2005-01-01 0.2448 2006-01-01 0.2153 2007-01-01 0.2046 2008-01-01 0.2186 2009-01-01 0.2353 2010-01-01 0.2570 2011-01-01 0.2723 2012-01-01 0.3117 2013-01-01 0.6281 2014-01-01 1.1739 2015-01-01 2.6997 2016-01-01 3.4851